Inspection lamp



A, L, STEVENS INSPECTION LAMP sept. 13, 1932.

Filed June l2, 1930 k ffm/wmf. 54% XQW Armi/Uff In l A fd 0J/ l Patented Sept. 13, 1932 UNITED STATES 'PATENTf OFFICE ARTHUR L. STEVENS, OF BUFFALO, N YORK, ASSiIGNOR TO THE 'VOL-'U-ME INC., (OF BUFFALO, NEW YORK TER C0.,

INSPECTION LAINE? Application led .Tune 12,

This invention relates to inspection lamps, and particularly to lamps for inspecting the interiors of drums and barrels or other containers.

5 An object of the invention is to provide an improved inspection lamp which will be automatically lig ted when placed in a position similar to that in which it is placed during use; which will be automatically shut off l 30 when the lamp is placed in another position,

and which may be manually shut oli' when the lamp is not in use or while being shipped, regardless of the position in which the lamp may be placed.

Another object of the invention is to provide an improved inspection lamp which may be safely used in the presence of inflammable vapors, and which will be relatively simple, compact, convenient and inexpensive.

Various other objects and advantages will be apparent from the following description of an embodiment of the invention, and the novel features will be particularly pointed hereinafter in connection with the appended claims.

lln the accompanying drawing:

Fig. 1 is an elevation, largely in longitudinal section, of a lamp constructed in accordance with this-invention.

80 Fig. 2 is a sectional elevation of one end thereof on a larger scale.

Fig. 3 is a similar sectional elevation of a portion of the lamp intermediate of its ends' Fig. 4 is a sectional elevation of a part of the stem of the lamp when the lamp is held in an inoperative position;

Fig. 5 is a sectional elevation of the light l bearing end of the lamp; and

Figs. 6 and 7 are diiierent views of the wire spring by which connection is made to one terminal of the battery unit.

In the illustrated embodiment of the invention, a cylindrical tube 1 is closed at one end by a removable cap 2, which is threaded into the tube 1. A ring gasket 3 is carried by the cap and compressed between a peripheral flange thereof and the adjacent end of the tube 1, so as to seal tightly the connec- 50 tion between the cap and tube. A coupling 1930. Serial No. 480,601.

4 is threaded into the other end vof the tube and carries an annular gasket 5 which is compressed between a peripheral flange of the coupling and the adjacent end of the tube, so as to seal tightly the junction between the coupling and the tube.

The coupling is provided with a stem 6 extending endwise therefrom, the other end of the stem being threaded into a head 7/ having alamp chamber or cavity 8. A reector 9 is secured, by a peripheral flange at its open end, against a shoulder 10 at the open end of the head, and the inner end of the reflector is provided with a threaded socket into which an electric light bulb 11 may be threaded adjustably to different eX- tents. A gasket ring 12 is disposed against the liange at the outer end of the reflector 9, and a lens or transparent member 13 is conlined against the gasket ring 12 by a lens holder 14 which is threaded upon a reduced portion of the open end of the head 7.

A gasket ring 15 is also interposed between the inner end of they holder 14 and the inner end of the reduced portion of the head. The holder 14 is provided with an internal angular flange 16 which overlies the periphery of the lens 13 and connes it against the gasket ring 12. An angular gasket ring 17 is also interposed between the rib or flange 16 and the lens. The gaskets l2, 15, and 17 serve to seal the outer end of the head 7, and prevent the movement of gases into and out of the lamp chamber 8.

A tube 18 of insulating material, such as fiber, is tightly fitted in the outer end of the stem 6 so as' to be held frictionally therein. A metal shell 19 is disposed and conlined within the tube 18. One end of the shell 19 is closed and receives a screw 20 upon its outer face, so as to form a terminal or post to which a wire 21 may be removably connected. The other end of the shell 19 is open and slidingly mounts a plunger 22, with the plunger projecting somewhat through the open end thereof.

The inner end of the plunger is slightly enlarged so as to form a flange 22a and the open end of the shell 19 is provided with an interim nal flange 23 which prevents the passage of the flange or head 22, and thus prevents complete ejection of the plunger. A sprin 24 is compressed between the inner end o the plunger and the closed end of the shell 19 and yieldingly urges the plunger outwardly and into engagement with the central contact in the base of the bulb 11.

A mercury switch 25 is disposed in the tubular stem 6. The switch comprises a closed glass tube having a pair of spaced electrodes or contacts 26 fused into one end thereof so as to project into the chamber of the tube and also outwardly therefrom. The wire 21 from the screw 2O has an insulating coating, and is connected to the outer end of 011e of the contact-s 26, the wire being coiled or given some slack as at 27, Fig. 1, for a purpose which will be explained hereinafter.

An insulated wire 28 is connected to the outer end of the other contact 26 and extends along the stem 6 into the coupling 4 where it is connected to an extension 29 of a metal connector washer 30. The washer 30 abuts against one face of disc 31 of insulating material and is secured thereto by a metal rivet 32 which passes through both the disc and the washer and also through one arm 33 of a U-shaped strip 34 of spring metal, such as phosphor bronze. The arm 33 abuts against that face of the disc 31 which is opposite from the washer 30. The arm 33 has a bent over lug 35 which is received in a slot or aperture 36 in the disc 31, which prevents rotation of the arm 33 on the rivet 32.

The other arm of the strip 34 is thus spaced from the disc so as tov yield slightly and serves as a spring contact which engages with the central electrode 37 of a battery unit 38 that may be received in the tube 1. Thebattery unit is removable and may comprise a plurality of flash light cells arranged end to end therein and abutting one another so as to connect themselves in series as usual in flash lights. The other end of the battery unit serves as the other electrode for the unit and is engaged by a spring 39 which is compressed between it and the inner end face of the cap 2.

The glass tube of the mercury switch 25 may be wrapped with a layer of cushioning materials 40 such as adhesive or friction tape, so that the glass of the switch tube will not directly engage the metal stem 6- and be broken thereb when the lamp is subjected to shocks or vi rations.

The glass tube contains a globule of mercu which moves alon the tube when the tube is tilted endwise. Vhen the globule is in the end of the tube having the inwardly projecting contacts 26, it closes a circuit between these contacts. When the globule reaches the other end of the tube the circuit is broken, and hence it will be seen that the circuit is made and broken within a closed tube.

To lubricate the mercury, a very small amount of alcohol, such as grain alcohol, is also placed in the tube before it is closed, to lubricate the merucry, and the amount of alcohol or similar lubricant is very important. A fraction of a drop of the alcohol, such as about 1A, drop has been found satisfactory. If a drop or more of the alcohol is used the mercury will froth. Just before the switch tube is filled it is heated slightly, so as to expand and drive out a part of its air and then the tube is sealed. When the tube has cooled, a slight vacuum exists in the tube so that the mercury may run freely from one end to the other of the tube.

During assembly, the slack or coil 27 in the wire 21 permits the attachment of the wire 21 to the screw 20 before the tube 18 and parts carried thereby are inserted in the outer end of the stem 6. The tube 1, coupling 4, stem 6, head 7, and reflector 9 are all metal and provide one conductor of a circuit between the lamp bulb and the battery unit, a circuit from the tube 1 to they battery unit being obtained through the spring 39.

When the lamp shown in Fig. 1, 'with the bulb end inclined downwardly or to the horizontal, the mercury globule will roll into the end of the tube having the contacts 26 and complete the c1rcuit from the battery unit to the lamp bulb 11, and the lamp will be lighted as long as the head end of the lamp is lowermost. When the lamp is inverted the switch 25 will be in the position shown in Fig. 34 and the circuit will be opened automatically.

When the lamp is not in use or is being shipped, the lighting of the lamp may be avoided by inserting the insulated disc 41, Fig. 1, between the spring 39 and t he adj acent end of the battery unit. The washer 41 may be reached and removed by first removing the cap 2, when the lamp is to be placed in commission.

The long stem 6 enables one to insert the head 7 and the stem through a bung hole of a barrel or drum, the lamp being lighted automatically when so inserted to enable one to readily inspect the inner surface of the barrel or drum which is illuminated by the lamp bulb 11. In as much as all contact parts are encased tightly within the lamp, there can be no ignition of outside gases by any possible arcs within the lamp. Such an inspection lamp is therefore safe to use under all conditions, even in the presence of inflammable or explosive vapors.

It will be understood that varlous changes in the details, which have been herein described and illustrated for the purpose of explaining the nature of the invention, may be made by those skilled in the art within the is held in the position' der, a. metal plunger reciprocating through one end of said tube into contact with the central base terminal of said bulb, aspring interposed bietween said plunger and the opposite end of said tube, and urging said plunger yieldingly against said bulb, and means extending through said stem and connected to said tube for supplying electric cury rent thereto.

2. An inspection lamp comprising a tubular handle having a stemn extending from one end thereof and with an internal shoulder at the junction between the handle and its stem, a disc of insulating material mounted on said shoulder, a U-shaped stri of spring metal having one arm of the U a utting the face of said disc within said handle, a rivet passing through said arm and said disc for attaching them together, and a metal washer end of the arm through which the rivet passes also mounted on said rivet between its head and the other face of said disc, and having a lateral extension towhich a wire may be attached, said disc having a slot, and the free having a tongue engaged in said slot to prevent rotation of said U-shaped strip on said j rivet, the free arm of said metal strip being disposed approximately centrallyA of said handle lfor engagement with the central terminal of a battery unit that may be mounted 'y in said handle.

3. An inspection lamp for use in the vicinity of inflammable vapors, comprising a tube, a cap removably secured to one end thereto, a gasket between the end of said tube and said cap to seal the same, a coupling removably attached to the other end of said tube, a gasket interposed between the coupling and the end of the tube to which it is attached to seal the joint between them, said coupling having a stem extending therefromand terminating in a hollow head, a light bulb mounted in said head, means for closing the outer end of said head and inclosing said bulb within the head and having a transparent member across the open end of said head, gasket means interposed between said head and said closing means to seal said head, said tube having a chamber of a size to receive and hold a battery unit, and means within said tube and stem for electrically connecting said unit and said bulb and controlling selectivelyl the lighting of said bulb,l said last named means 5 including .a closed tube `mercury switch mounted within said stem and closing the circuit between the battery and the bulb when the stem is downwardly inclined from said coupling.

ARTHUR L. STEVENS. 

